1. Field of the Invention
This invention relates to a semiconductor device having a low dielectric constant film and a manufacturing method thereof.
2. Description of the Related Art
A chip size package (CSP) having about the same size and dimensions as a semiconductor substrate is known as a semiconductor device mounted on small electronic equipment such as portable electronic equipment. A CSP which has been packaged in a wafer state and diced into semiconductor devices is called a wafer level package (WLP).
Jpn. Pat. Appln. KOKAI Publication No. 2004-349461 has disclosed a semiconductor device, and this semiconductor device comprises: a wiring line extending on the upper surface of an insulating film over a connection pad formed on a semiconductor substrate; a large number of columnar electrodes provided on the upper surface of a connection pad portion formed on one end of the extending wiring line; and a sealing film formed over the wiring line between the columnar electrodes on the upper surface of the insulating film. The sealing film is provided so that its upper surface is flush with the upper surfaces of the columnar electrodes, and solder balls are provided on the upper surfaces of the columnar electrodes.
On the other hand, in some of the semiconductor devices as described above, an interlayer insulating film/wiring line stack structure composed of interlayer insulating films and wiring lines is provided in an integrated circuit formed on one surface of a semiconductor substrate. In this case, if the distance between the wiring lines of the interlayer insulating film/wiring line stack structure is reduced due to miniaturization, the capacity between the wiring lines increases, and a signal transmitted through these wiring lines is more delayed.
A low dielectric constant material called, for example, a low-k material is attracting attention as the material of the interlayer insulating film that makes improvements. This material has a dielectric constant lower than 4.2 to 4.0 which is the dielectric constant of silicon oxide generally used as the material of the interlayer insulating film. The low-k material includes, for example, SiOC which is silicondioxide (SiO2) doped with carbon (C), and SiOCH further containing H. For a further reduction in dielectric constant, a porous low dielectric constant film containing air is also considered.
However, the disadvantage of a semiconductor device having the above-described low dielectric constant film, in particular, the hollow porous low dielectric constant film is that the film is low in mechanical strength, susceptible to water, and apt to come off a foundation layer.